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Alternative Energy Forum including wind, solar, inverter discussionsenWed, 19 Dec 2018 10:01:35 GMTvBulletin60http://forums.mikeholt.com/images/misc/rss.pnghttp://forums.mikeholt.com/
300A Supply Side Interconectionhttp://forums.mikeholt.com/showthread.php?t=195364&goto=newpost
Fri, 14 Dec 2018 01:08:51 GMTI am going to install a Photovoltaic system for an orphanage here in Guatemala. There will be 7 inverters with a maximum current of 42A and 240...I am going to install a Photovoltaic system for an orphanage here in Guatemala. There will be 7 inverters with a maximum current of 42A and 240 Volts. The area is quite large with 150 children and 50 adults living on the grounds. The energy used has a minimum current of 65A 24 hours a day. The maximum is 135A mostly between 6PM and 10PM. They have a large generator with an automatic cutoff switch. I would like to connect the inverters on the line side of the inverter between the cut off switch and the meter. I need to find a clean way to connect large cables basically like a tap. The existing connections are bolted on compression lugs. Can someone recommend junction blocks to join together three large compression lugs? I will combine the inverter outputs before the supply side connection. I really don't work with that type of connection much and local suppliers are not much help.
]]>Photovoltaic Forumwwstrickhttp://forums.mikeholt.com/showthread.php?t=195364Scope of Article 691.1http://forums.mikeholt.com/showthread.php?t=195315&goto=newpost
Tue, 11 Dec 2018 18:24:25 GMT"...and not under exclusive utility control."

So, my question is what if it is under utility control?
]]>Photovoltaic Forumkingpbhttp://forums.mikeholt.com/showthread.php?t=195315SMA rapid shutdown not code compliant after JAN 1st?http://forums.mikeholt.com/showthread.php?t=195288&goto=newpost
Mon, 10 Dec 2018 20:44:10 GMTAm I interpreting NEC 2017 correctly in that the SMA RSS solution [Box (flat white box at array on roof) and Controller (red button switch) ]
will no longer be Code compliant next year?

I don't understand 690.12 (B) (2) (3). Does this mean it can in fact be used?
]]>Photovoltaic ForumZeehttp://forums.mikeholt.com/showthread.php?t=195288Solar questionhttp://forums.mikeholt.com/showthread.php?t=195274&goto=newpost
Sun, 09 Dec 2018 23:59:03 GMTI have a service upgrade I am doing, two family house. 2nd floor unit has solar system already installed to the 100 amp panel. It’s tapped onto the...I have a service upgrade I am doing, two family house. 2nd floor unit has solar system already installed to the 100 amp panel. It’s tapped onto the line side of the main breaker, wires come from a 2 circuit can with a 2 pole 50 amp breaker. Why are they tapped to the line side, between meter and panel vs just going into the panel on a 2 pole 50 amp breaker?
]]>Photovoltaic ForumJoeyD74http://forums.mikeholt.com/showthread.php?t=195274Air conditioner disconnect for inverter?http://forums.mikeholt.com/showthread.php?t=195264&goto=newpost
Sat, 08 Dec 2018 23:41:33 GMTSo it was recently brought to my attention that this type of disconnect...So it was recently brought to my attention that this type of disconnect is insanely cheap compared to what we've been using to comply with the grouped disconnect requirement when an inverter is not near the point of interconnection. 690.15 in the 2014 NEC. The safety switch has always been what I've seen in the solar industry, and I've always just done what was done before. But there's a lot of money to be saved here, so I'm asking myself, if it's good enough for the air conditioning guys, why not good enough for solar inverters?

(Before anything else: this thread does not pertain to disconnects required by utilities. Just NEC requirements.)

Anybody using these? (for small inverters, up to 48A output)
Anyone aware of a good reason not to use them?

Thoughts:

First, 705.22 includes:

Quote:

" the disconnecting means shall consist of ... switch(es) or circuit breaker(s) with the following [feature]:
...
(2) Externally operable without exposing the operator to live parts...

It seems like perhaps this rules out a pull-out type disconnect, but we'll always have another disconnect that can comply with 705.12. This is just to comply with 690.15. (Also, is there a good reason that 705 should rule out pull out disconnects?)

Second, the 2017 NEC changes things up quite a bit in 690. We now have similar language as above in 690.15(D), except it says "externally operable without exposing the operator to contact with energized parts..." (emphasis added). It also includes "A load break fused pull out switch" among the list of options for an 'equipment disconnecting means'. I find this, er, interesting. First, why must the pull out switch be fused? Second, if a type of pull out switch is allowed, then do pull out switches not expose the operator to live parts? Or does a pull out switch "expose the operator to live parts" but not expose them "to contact with energized parts"?

Does this language about exposure to live parts appear in any non-solar related requirements for disconnects elsewhere in the code?

Premium panel micro inverter systems produce 20% more energy than a central inverter system of the same size and offer by far the highest safety and reliability (99.7% up-time) and longest MTBF (Mean Time Between Failures) of any PV system on the market today. This 27.3 kW system is equivalent to a 32.8 kW central inverter system in annual energy harvest.

I havent heard the term "premium panel" before. Obviously micro inverters have some production advantages, but 20% more seems way high, even with a lot of differential shading. Thoughts?
]]>Photovoltaic Forumelectrofelonhttp://forums.mikeholt.com/showthread.php?t=195059Line-Side Interconnection on Building Disconnect Switchhttp://forums.mikeholt.com/showthread.php?t=195019&goto=newpost
Tue, 27 Nov 2018 23:20:00 GMTHello,

I want to interconnect a total of 150A of solar line side of a 400A building disconnect switch. The problem that I'm not sure of is what would be the best method/practice of interconnection. Not having much experience any advice is greatly appreciated. I attached a picture of the interconnection point for reference. Would it be best to see if I could replace the single set of lugs to double lugs or get a new disconnect switch with built-in 2 lugs per phase? Money isn't a factor here. Also, I would just need to keep a 400A disconnect switch frame since the solar offset the utility feed?

Thanks again

Attached Images

]]>Photovoltaic Forumbaserunner4http://forums.mikeholt.com/showthread.php?t=195019panel failure more common with micros?http://forums.mikeholt.com/showthread.php?t=195014&goto=newpost
Tue, 27 Nov 2018 22:12:13 GMTI have had almost no solar panels fail over the years. The few panels that had issues seem to be connected to micro-inverters and not string...I have had almost no solar panels fail over the years. The few panels that had issues seem to be connected to micro-inverters and not string inverters.
1. Does anyone notice this pattern?
2. Is there any reason for it?
3. In the most current case V-DC from panel is low. It's partially producing, but way less than it should. Why would that be?
(micro has been replaced so clearly not the culprit)
]]>Photovoltaic ForumZeehttp://forums.mikeholt.com/showthread.php?t=195014PV System Interconnectionhttp://forums.mikeholt.com/showthread.php?t=194876&goto=newpost
Mon, 19 Nov 2018 15:40:52 GMTHello,

I'm doing the interconnection design of a 1200A photovoltaic system, the customer has a relatively old 2000A switchboard for the main disconnect medium, which is also 2000A.

In my design, I am using 5 inverters with an OCPD of 225A each, and they are connecting in a switchboard of 2000A, the feeder of this control panel has been interconnected with the panel of my client.

I have two doubts:

1. Is it allowed to interconnect my pv system to the main breaker of my client?

2. As I understand, I have to design my pv system up to 1.20% of the main breaker, right?

The issue is that the switchboard of my client is of 2000A, that means that I can connect only a PV system of 400A. then, I think that I have to change the switchboard of client from 2000A to 3000A with a 2000A main breaker, right?